Monopentamethylcyclopentadienyl isocyanide, amine and imido tantalum(V) complexes. X-ray crystal structure of [TaCp*Cl4(CN-2,6-Me2C6H3)]

[TaCp★Cl4](Cp★ = η5-C5Me5) reacts with isocyanides and amines to give the pseudo-octahedral adducts [TaCp★Cl4L] (L = 2,6-Me2C6H3NC, 1; 2,4,6-Me3C6H2NC, 2; tBuNC, 3; or C6H5NH2, 4). Reduction of 1, or alternatively of [TaCp★Cl4] in the presence of stoichiometric amounts of isocyanide, with two equivalents of Na/Hg gives the diamagnetic pseudo-octahedral tantalum(III) complex, [TaCp★Cl2(CN-2,6-Me2C6H3)35. Reaction of 4 with two equivalents of LiNEt2 affords the pseudo-octahedral imido complex [TaCp★Cl2(NC6H5). 6. All the complexes were characterized by usual IR and NMR spectroscopic methods and the molecular structure of I was confirmed by X-ray diffraction methods

Diastereoselective insertion of isocyanide into the alkyl metal bond of methylbenz[e]indenyl ansa-zirconocene complexes

Alkylation of ansa-zirconocene [Zr{(η5-C5H5)SiMe2(MBI)}Cl2] (MBI = η5-2-Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5-C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono-alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5-C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI-unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6-xylyl isocyanide to give the iminoacyl compounds [Zr{(η5-C5H5)SiMe2(MBI)}R{CR[η2-N-(2,6-xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes were characterized by NMR spectroscopy and the X-ray molecular structures of the dibenzyl and the imino-benzyl compounds were determined. The catalytic activity for ethene polymerization and ethene/1-hexene copolymerization of the dichloro zirconocenes [Zr{(η5-C5H5)EMe2(MBI)}Cl2] (E = C, Si), activated with methylalumoxane (MAO), was measured.Repsol-YP

Allylsilylcyclopentadienyl Group 4 metal complexes: synthesis, structure and reactivity

(Allyldimethyl)silyl-substituted cyclopentadiene C5H5SiMe2(CH2CH /CH2) (1) and indene C9H7 /1-SiMe2(CH2CH /CH2) (2)\ud were synthesized by reaction of SiMe2(CH2CH /CH2)Cl with NaC5H5 or LiC9H7, respectively. Metallation of 1 with n-BuLi and\ud TlOEt gave the corresponding lithium 3 and thallium 5 salts. The disilylcylopentadienes C5H4 /1-SiMe3 /1-SiMe2(CH2CH /CH2) (6)\ud and C5H4 /1,1-[SiMe2(CH2CH /CH2)]2 (7) were prepared by reaction of 3 with the corresponding chlorosilanes. Compound 7\ud reacted with TiCl4 to give the monocyclopentadienyl compound [Ti{h5\ud -C5H4SiMe2(CH2CH /CH2)}Cl3] (8), while 5 was used to\ud prepare the titanocenes [Ti(h5\ud -Cp){h5\ud -C5H4SiMe2(CH2CH /CH2)}Cl2] (Cp /C5H4SiMe2(CH2CH /CH2) 9, C5H5 10, C5Me5 11) by\ud reaction with the appropriate TiCpCl3 derivative. The related dicyclopentadienyl [Zr{h5\ud -C5H4SiMe2(CH2CH /CH2)}2Cl2] (12),\ud [Zr(h5\ud -C5H5){h5\ud -C5H4SiMe2(CH2CH /CH2)}Cl2] (13), and indenyl [Zr(h5\ud -C5H5){h5\ud -C9H6SiMe2(CH2CH /CH2)}Cl2] (14) zirconium\ud derivatives were isolated by reaction of ZrCl4 and Zr(h5\ud -C5H5)Cl3 /DME with the lithium salts 3 and 4, respectively.\ud Alkylation of the metallocene complexes using MeLi, MgMeCl, Mg(CH2Ph)Cl and Mg(CH2Ph)2(THF)2 afforded the monomethyl\ud titanium [Ti(h5\ud -C5H5){h5\ud -C5H4SiMe2(CH2CH /CH2)}ClMe] (15) and the dialkyl cyclopentadienyl [M(h5\ud -C5H5){h5\ud -C5H4SiMe2\ud (CH2CH /CH2)}R2] (R /Me, M /Ti 16, Zr 18; R /CH2Ph, M /Ti 20, Zr 22), [Zr{h5\ud -C5H4SiMe2(CH2CH /CH2)}2R2] (R /Me\ud 17, CH2Ph 21) and indenyl derivatives [Zr(h5\ud -C5H5){h5\ud -C9H6SiMe2(CH2CH /CH2)}R2] (R /Me 19, CH2Ph 23). The molecular\ud structure of 11 was studied by X-ray diffraction methods. The reactions of the dialkyl derivatives with B(C6F5)3 were monitored by\ud NMR spectroscopy at variable temperature. The catalytic activity of the dichloro zirconium complexes in the presence of\ud methylalumoxane (MAO) for ethylene polymerization was determined.Financial support of our work by MCyT (Project\ud MAT2001-1309) is gratefully acknowledged. G.H., G.M\ud and J.C are grateful to to the Alexander von HumboldtStiftung,\ud MEC and CAM for fellowships

Silyl and siloxanediyl cyclopentadienyl titanium and zirconium complexes: synthesis and reactivity. X-ray molecular structure of [Zr{η5-C5H4SiMe2(μ-OH)}(μ-Cl)Cl2]2

Chloro(dimethyl)silyl-η5-cyclopentadienyl group 4 metal complexes of the type [M(η5-C5H4Cl)Cl3] (Full-size image (<1 K)) react with thallium salts Tl(C5H4R) (R = H, SiMe3) to give mixed dicyclopentadienyl derivatives [M(η5-C5H4R)(η5-C5H4SiMe2Cl)Cl2], (M = Ti, R = H 3, R = SiMe34; M = Zr, R = H 5, R = SiMe36) in high yield. Hydrolysis of complexes 3 and 4 affords the dinuclear complexes [Ti(η5-C5H4R)Cl2]2{μ-[(η5-C5H4SiMe2)2O]}] [R = H 7, R = SiMe38) containing a siloxanyl bridge, by elimination of two equivalents of HCl. Reactions of complexes 1 with hydroxo containing reagents such as anhydrous LiOH and SiPh2(OH)2 give the derivatives [Ti(η5-C5H4SiMe2Cl)Cl2]2(μ-O)], 9 and Ti[μ-(η5-C5H4SiMe2OSiPh2-η1-O)]Cl2, 10 identified by analytical, spectrometric and spectroscopic data. Treatment of analogous complex 2 with water produces the dimeric monocyclopentadienyl zirconium trichloride adduct [Zr(η5-C5H4SiMe2OH)Cl3]2, 11. Compound 11 has been characterized by X-ray crystallography.Universidad de AlcaláConsejería de Educación de la Comunidad de Madri

Dicyclopentadienyl zirconium and hafnium complexes with the bridged (dimethylsilanodiyl)dicyclopentadienyl [(SiMe2)(η5-C5H4)2]2 ligand. X-ray molecular structure of [Zr{(SiMe2)(η5-C5H4)2}(CH2Ph)]2(μ-O)

Reaction of the bridged (dimethylsilanediyl)dicyclopentadienyl dilithium salt [(SiMe2)(C5H4)2Li2] with MCl4, in toluene, gave the zirconium and hafnium complexes [M{(SiMe2)(η5-C5H4)2}Cl2] [M=Zr (1), Hf (2)]. Addition of two equivalents of M′R (M′=MgCl, R=CH3; M′=Li, R=CH2CMe2Ph; M′=MgBz, R=CH2Ph) to toluene or diethyl ether solutions of [M{(SiMe2)(η5-C5H4)2}Cl2] afforded the dialkyl derivatives [M{(SiMe2)(η5-C5H4)2}R2] [R=CH3, M=Zr (3), Hf (4); R=CH2CMe2Ph, M=Zr (5), Hf (6); R=CH2Ph, M=Zr (7)]. Compound 1 reacted with LiMe and Mg(CH2Ph)2(THF)2 in the presence of a stoichiometric amount of water to give the μ-oxo derivatives [Zr{(SiMe2)(η5-C5H4)2}R]2(μ-O) [R=CH3 (8), CH2Ph (9)]. The X-ray molecular structure of [Zr{(SiMe2)(η5-C5H4)2}(CH2Ph)]2(μ-O) (9) has been determined by diffraction methods. Its most remarkable feature is the planarity of the BzZrOZrBz and the linearity of the ZrOZr systems.We acknowledge the Dirección General de Investigación Científica y Técnica (Spain) for financial support of this research (Project PB97-0776)

Dicyclopentadienyl titanium and zirconium complexes with the double bridged bis(dimethylsilanodiyl) dicyclopentadienyl [(Me2Si)2(η5-C5 H3)2]2- ligand: X-ray molecular structure of [Ti{(SiMe2)2(η5-C5H3)2}Me2]

The reaction of the doubly bridged bis(1,1′,2,2′-dimethylsilanodiyl)-η5-dicyclopentadienyl titanium and zirconium complexes Full-size image (<1 K) with water gave the μ-oxo derivatives Full-size image (<1 K). Addition of one equivalent of M′R (M′ = MgCl, R = CH3, CH2SiMe3; M′ = Li, R = CH2CME2Ph) to toluene or diethyl ether solutions of Full-size image (<1 K) afforded the chloro alkyl derivatives [M{(SiMe2)2(η5-C5H3)2}CIR]Full-size image (<1 K). Compounds 3 and 4 reacted with [CPh3][B(C6F5)4] at −78°C in CD2Cl2 leading to the cationic species Full-size image (<1 K) as demonstrated by NMR spectroscopy. The titanium(III) and zirconium(III) serivatives [M{(SiMe2)2(η5-C5H3)2} (μ-Cl)2 (M = Ti (12), Zr (13)) were obtained by reduction of 1 amd 2 with one equivalent of sodium amalgam. The X-ray molecular structure of [Ti{(SiMe2)2(η5-C5H3)2}Me2] (3) has been determined by diffraction methods.Financial support for this research by DGICYT (Project PB92-0178-C) is gratefully acknowledged. A,M. is grateful to Consejeria Educación (CAM) for a fellowship

Reactivity of chlorodimethylsilyl-η5-cyclopentadienyltrichlorotitanium\ud with nitrogen based donors. X-ray molecular structure of\ud [Ti{η5-C5H4SiMe2[η1-N(2,6-Me2C6H3)]}Cl2]

This paper reports the reactivity of [Ti(η5-C5H4SiMe2Cl)Cl3], 1 towards nitrogen based donor reagents. Complex 1 reacts with lithium benzamidinato Li[PhC(NSiMe3)2] to afford [Ti(η5-C5H4SiMe2Cl){PhC(NSiMe3)2}Cl2] 2 and with lithium amide LiNMe2 to produce [Ti(η5-C5H4SiMe2NMe2)(NMe2)3] 3. The latter compound was converted into the dihalide derivatives [Ti(η5-C5H4SiMe2NMe2)(NMe2)X2] [X=Cl (4) and Br (5)] by reaction with SiMe3X (X=Cl or Br, respectively). The constrained geometry derivatives [Ti{η5-C5H4SiMe2(η1-NR)}Cl2] (R=C6H56, 2,6-Me2C6H37 and 2-Me-6-iPr-C6H38) have been synthesized by treatment of 1 with the corresponding primary aryl amines H2NR. Complex 7 was readily converted into the dialkyl and diamido compounds [Ti{η5-C5H4SiMe2[η1-N(C6H3Me2)]}X2] (X=Me (9), CH2Ph (10), CH2SiMe3 (11) or NMe2 (13)) by metathesis using Grignard or organolithium reagents and into the monoalkyl derivative [Ti{η5-C5H4SiMe2[η1-N(C6H3Me2)]}MeCl] (12) by reaction with AlMe3. The molecular structure of complex 7 [Ti{(η5-C5H4SiMe2[η1-N(2,6-Me2C6H3)]}Cl2] was established by X-ray crystallography.We are grateful to the DGICYT (Project PB-92-0178-C) and University of Alcalá for financial support of this research

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zr{η5-C5H4(SiMe2CH2Ph)}(CH2Ph)3]

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zr{η5-C5H4(SiMe2CH2Ph)}(CH2Ph)3]We are grateful to the DGICYT (Project PB-92-0178-C) and University of Alcalá for the financial support of this research

Alkyl and alkylidene imido cyclopentadienyl tungsten complexes

This paper reports the alkylation of the cyclopentadienyl imido tungsten complexes [WCp′(NtBu)Cl3] (Cp′=η5-C5H5, η5-C5Me5) with β-hydrogen containing alkyl groups to render halo alkyl and trialkyl complexes [WCp′(NtBu)Cl3−nRn] (R=Et, n-Pr). Thermal decomposition of the trialkyl compounds gives the alkylidene derivatives [WCp′(NtBu)(CHR)(CH2R)] (R=Me, Et) by α-hydrogen elimination. All of the compounds were characterized by NMR spectroscopy and the molecular structure of [W(η5-C5Me5)(NtBu)Et3] was determined by X-ray diffraction methods.The authors acknowledge DGICYT (project PB97-0677) for financial support

Neutral and cationic di(tert-butyl) cyclopentadienyl titanium, zirconium and hafnium complexes. Dynamic NMR study of the ligand-free cations [M(1,3-tBu2-η5-C5H3)(η5-f5H5)(CH3)]+(M=Zr, Hf)

Group 4 metal complexes containing the di(tert-butyl)cyclopentadienyl ligand (l,3-tBu2-r/5-CsH3) have been synthesized. The\ud reaction of a mixture of 1,3- and 1,4-di(tert-butyl)cyclopentadiene isomers with KH in THF at -78°C gives the salt K+[(1,3 -\ud tBu2CsH3)]-(THF)I_3 2 as a white solid. Treatment of 2 with chlorotrimethylsilane in a 1:1 molar ratio gives the air-stable\ud trimethylsilylcyclopentadienyl derivative Si(1,3-tBu2C5H3XCH3)3 3. The silyl derivative 3 is an excellent precursor for monocyclopentadienyl\ud trichlorotitanium and zirconium compounds M(1,3 -t Bu 2-r/5-C 5 H 3)C13 [M = Ti (4), Zr (5)]. Addition of a stoichiometric amount\ud of water in the presence of NEt 3 to a toluene solution of 4 affords the oxo trimer compound [Ti(1,3-tBu2-~75 - CsH3)CI( p,-O)] 3 6. The\ud reaction of 4 with 2 equiv, of LiMe affords the chloro dimethyl derivative Ti(1,3-tBu2-'r/5-CsH3)CI(CH3)2 7. The mixed dicyclopentadienyl\ud compounds M(1,3-tBu2-r/5-CsH3XCsHs)CI2 [M = Ti (8); Zr (9)] were prepared by reaction of complexes 4 and 5 respectively with\ud TI(CsHs). Treatment of complexes (8) and (9) with the appropriate alkylating reagent and molar ratio, in hexane at -78 °C, gives the\ud chloro alkyl derivatives M(1,3-tBu2-@-C5H3XCsHs)CIR [M = Ti, R = Me (10); M = Zr, R = Me (11), Bz (12)] or the dialkyl\ud complexes M(1,3-tBu2-@-CsH3)(CsHs)Rz [M = Ti, R = Me (13); M = Zr, R = Me (14), Bz (15), Nf (16)]. When 8 reacts with 2 equiv.\ud of MgBz2(THF) 2 or LiCH2CMe2Ph the metallacyclic complexes Ti(1-tBu-3-CMe2CH~-r/5-C~Ha)(CsHs)R [R = Bz (17); Nf (18)] were\ud isolated as red oils at room temperature, with the elimination of toluene or ten-butyl benzene respectively. The previously reported\ud cationic mono 1,3-di(tert-butyl)cyclopentadienyl dibenzyl zirconium species [Zr(1,3 -t Bu 2-'05-C 5 H 3 XCH 2 Ph) 2 ] + (19) can be stabilized\ud by reaction with tBuNC or PMe 3, in CD2C12 at -78°C, and the formation of the new cationic species [Zr(1,3-tBu2-r/5-\ud CsHa)(L)(CH2Ph)2] + [L=tBuNC (20); PMe 3 (21)] was identified by NMR spectroscopy. The reaction of B(CrFs) 3 with the\ud monocyclopentadienyl trimethyl derivatives M(1,3-tBu2-r/5-CsH3XCH3)3 [M = Ti (22), Zr (23)], in the presence of PMe 3, gives the\ud cationic species [M(I,3-tBu2-@-C~H3)(PMe3)2(CH3)2] + [M = Ti (24); Zr (25)], obtained as orange-yellow solids, stable at room\ud temperature. The reaction of B(C6Fs) 3 with the metallocene dimethyl derivatives M(1,3-tBu2-r/5-CsHa)(@-CsHs)(CH3)z [M = Zr (14);\ud Hf (26)], in a 1:1 molar ratio and in hydrocarbon solvents gives the cationic derivatives [M(1,3-tBu2-@-CsH3)(@ -\ud CsHsXCH3)]+[(CH3)B(CrFs)3] - [M = Zr (27); Hf (28)] as yellow oils which can be stored for weeks under an inert atmosphere. When\ud the same reactions of (14) and (26) with B(C6Fs) 3 are carried out in a 2:1 molar ratio at room temperature, the complexes\ud {[M(1,3-tBu2-@-CsH3X@-CsH5)Me]2(/.L-Me)}[MeB(C6Fs)3] [M =Zr (29), Hf (30)] can be obtained as a mixture of syn- and\ud anti-isomers as shown by NMR spectroscopic observations. The formation of (29) and (30) implies the stabilization of the 14-electron\ud cationic intermediate by interaction with one methyl group of the neutral complexes (14) and (26). Complexes (27) and (28) undergo\ud heterolytic dissociation of the Metal-MeB(C6Fs) 3 bonds, leading to the formation of the free [M(I,3-tBu2-r/5-CsH3)(r/5-CsHs)(CH3)] +\ud 14-electron species, verified by 1H DNMR spectroscopy. When compound (27) was heated at 50°C the metallacyclic cation\ud [Zr(1-tBu-3-CMezCH2-@-C5H3)(@-CsHs)] + (31) was formed. The alkyl derivatives synthesized and reported herein, activated with MAO, B(C6Fs) 3 or [Ph3C][B(C6Fs)4], polymerize ethylene with very low activity. The molecular structure of [Ti(1,3-tBu2-r/5-\ud C5H3)C1(/x-O)] 3 6 has been determined by X-ray diffraction methods.Financial support for this research by DGICYT (Project PB92-0178C) is gratefully acknowledged. J.I.A.\ud acknowledges Repsol Petróleo S.A. for a fellowship. A.M. is grateful to Consejeria Educaci6n (CAM) for a fellowship